class LetterDisplayUtils {
  static String getIndexLetter(int index) {
    switch (index) {
      case 0:
        return "A";
      case 1:
        return "B";
      case 2:
        return "C";
      case 3:
        return "D";
      case 4:
        return "E";
      case 5:
        return "F";
      case 6:
        return "G";
      case 7:
        return "H";
      case 8:
        return "I";
      case 9:
        return "J";
      case 10:
        return "K";
      case 11:
        return "L";
      case 12:
        return "M";
      case 13:
        return "N";
      case 14:
        return "O";
      case 15:
        return "P";
      case 16:
        return "Q";
      case 17:
        return "R";
      case 18:
        return "S";
      case 19:
        return "T";
      case 20:
        return "U";
      case 21:
        return "V";
      case 22:
        return "W";
      case 23:
        return "X";
      case 24:
        return "Y";
      case 25:
        return "Z";
      default:
        return "未记录";
    }
  }

  //限制字数
  static String maxLength(String content) {
    if(content == null){
      return "";
    }
    return content.length > 13 ? content.substring(0, 13) + "..." : content;
  }
}
